Light-emitting-diode (LED) lamps are known in the art. A LED lamp is a lamp that uses LEDs as the source of light. In such lamps, multiple diodes may be used for e.g. for increasing the output power of the lamp or for providing a white light when utilizing LEDs that emit light in a narrow band of wavelengths (as opposed to for instance using phosphor converted LEDs, which may emit light in the whole visible spectrum, thereby providing a more-or-less white light). LED lamps may be used for general lighting or even more specific lighting as the color and the output power may be tuned.
Generally, a lamp or a lighting device comprises a light source arranged to generate light, which light source is arranged at, or at least connected to, a driver circuitry arranged in a housing. Further, the light source is arranged within an encapsulating envelope usually having the shape of a bulb. In addition to providing maximum light output and/or a specific color of light, the design of a lighting device needs to take into account the evacuation of heat generated by the light source and the driver. Lifetime and reliability of e.g. LEDs and the driver components are important product characteristics, which are strongly connected to the operating temperatures of the involved components.
A prior art retrofit light bulb lamp is typically realized with a retrofit cap, e.g. of bayonet type or an Edison screw type, which is mechanically connected to a lamp housing in which a driver is arranged. The driver comprises the necessary electronics to drive a light source of the lamp. The light source is typically arranged within an envelope, being a glass bulb, so that light being generated by the light source may exit the lamp via the glass bulb. The lighting device comprises two main heat sources: the driver and the light source. When the light source comprises remote phosphor LEDs, also the remote phosphor generates some amount of heat. To carry off the heat generated in the driver and the light source, they are connected to a heat sink. Typically the lamp housing is used for cooling the lamp, e.g. it is designed to be a heat sink for the driver and the light source.
WO 2009/012806 A1 discloses a lamp comprising at least one light source, which is arranged on top of, and being thermally coupled to, a hollow cooling body, i.e. a heat sink, arranged within the lamp housing, which is connected to the cap. The cooling body is arranged such that heat can be dissipated from the light source. The cooling body is further arranged to, at a position separated from the top of the cooling body, fixate a supply board, i.e. a driver, such that the supply board is separated from the lighting unit. The cooling body is arranged such that heat can be dissipated also from the supply board. Although being separated from each other, the heat generated by the main heat sources of the lighting device is dissipated from the same cooling body, and the heat generated in e.g. the light source will thus influence the temperature of the driver.